LibWeb: Add option to TemporaryExecutionContext to prepare for callbacks

In the cases where spec authors have us directly interact with promises
in a task source context, we need to prepare the backup settings object
stack as well as push an actual execution context to the JS VM.

Userland/Libraries/LibWeb/HTML/Navigation.cpp

@@ -1067,7 +1067,7 @@ bool Navigation::inner_navigate_event_firing_algorithm(
 
     // 31. Prepare to run script given navigation's relevant settings object.
     // NOTE: There's a massive spec note here
-    TemporaryExecutionContext execution_context { relevant_settings_object(*this) };
+    TemporaryExecutionContext execution_context { relevant_settings_object(*this), TemporaryExecutionContext::CallbacksEnabled::Yes };
 
     // 32. If event's interception state is not "none":
     if (event->interception_state() != NavigateEvent::InterceptionState::None) {

Userland/Libraries/LibWeb/HTML/Scripting/TemporaryExecutionContext.cpp

@@ -9,15 +9,20 @@
 
 namespace Web::HTML {
 
-TemporaryExecutionContext::TemporaryExecutionContext(EnvironmentSettingsObject& environment_settings)
+TemporaryExecutionContext::TemporaryExecutionContext(EnvironmentSettingsObject& environment_settings, CallbacksEnabled callbacks_enabled)
     : m_environment_settings(environment_settings)
+    , m_callbacks_enabled(callbacks_enabled)
 {
     m_environment_settings.prepare_to_run_script();
+    if (m_callbacks_enabled == CallbacksEnabled::Yes)
+        m_environment_settings.prepare_to_run_callback();
 }
 
 TemporaryExecutionContext::~TemporaryExecutionContext()
 {
     m_environment_settings.clean_up_after_running_script();
+    if (m_callbacks_enabled == CallbacksEnabled::Yes)
+        m_environment_settings.clean_up_after_running_callback();
 }
 
 }

Userland/Libraries/LibWeb/HTML/Scripting/TemporaryExecutionContext.h

@@ -15,11 +15,17 @@ namespace Web::HTML {
 // this is a workaround to temporarily push an execution context.
 class TemporaryExecutionContext {
 public:
-    explicit TemporaryExecutionContext(EnvironmentSettingsObject&);
+    enum class CallbacksEnabled {
+        No,
+        Yes,
+    };
+
+    explicit TemporaryExecutionContext(EnvironmentSettingsObject&, CallbacksEnabled = CallbacksEnabled::No);
     ~TemporaryExecutionContext();
 
 private:
     EnvironmentSettingsObject& m_environment_settings;
+    CallbacksEnabled m_callbacks_enabled { CallbacksEnabled::No };
 };
 
 }